Flares are pyrotechnic devices designed and configured to emit intense electromagnetic radiation at wavelengths in the visible region (i.e., light), the infrared (IR) region (i.e., heat), or both, of the electromagnetic radiation spectrum without exploding or producing an explosion. Conventionally, flares have been used for signaling, illumination, and defensive countermeasure in civilian and military applications. In such applications, illumination flares are typically launched above ground or water areas where enemy personnel and/or vehicles are suspected to be present. The illumination provided by the illumination flare facilitates visual detection of the enemy personnel and/or vehicles, providing more precise identification of target locations at which to aim ordnance. The illuminating effect provided by the illumination flare is conventionally enhanced by equipping the flare with a parachute, which increases the flight time by slowing the rate of descent of the illumination flare. The deployment of the parachute can also provide a force for activating an igniter contained within the casing of the illumination flare.
One common type of illumination flare is a NIR illumination flare. As used herein, the term “NIR illumination flare” means and includes a flare having a primary NIR (i.e., radiation at a wavelength of from 0.700 micrometers to 0.900 micrometers) output facilitating the illumination of a target (e.g., a battlefield) such that the target can be seen with a device (e.g., a NIR vision device, such as NIR-sensitive night vision goggles) configured and operated to view emissions in the NIR spectrum. NIR illumination flares generate a significant amount of NIR radiation while limiting the generation of visible radiation, thereby facilitating relatively covert illumination of a target. However, a number of problems have been encountered in the development of suitable NIR emitting illumination compositions for use in such NIR illumination flares. For example, conventional illumination compositions exhibit one or more of insufficient NIR radiation generation during combustion, excessive visible radiation generation during combustion (e.g., a poor ratio of generated NIR radiation to generated visible radiation), insufficient (e.g., low) combustion rate, non-uniform combustion, undesired breakup (also known as “chunking”) of the illumination composition during use of the NIR illumination flare, excessive ash (e.g., soot) formation during combustion, deleterious environmental impact, poor aging, and excessive production cost. Achieving an improvement in one of the foregoing properties often results in a decline in at least one other of the properties.
It would be desirable to produce an illumination composition that mitigates at least one of the undesirable properties (e.g., low NIR radiation generation, excessive visible radiation generation, low combustion rate, non-uniform combustion, undesired breakup, excessive ash formation, negative environmental impact, poor aging, excessive production cost, etc.) encountered with conventional NIR emitting illumination compositions without significantly decreasing at least one other of the desirable properties of such illumination compositions.